Computer system



May il, i948.

R. L. SNYDER, JR., ETAL COMPUTER SYSTEM Filed Dec. 2v, 194s Qddddd N Patented May 11, 1948 COMPUTER SYSTEM Rionero L. Snyder, Jr., and Robert n. Gooarioh, Princeton, N. J., assignors to Radio Corporation of America, a corporation of Delaware Application December 27, 1943, Serial No. 515,842

8 Claims. 1

This invention relates to computer systems such as are utilized to derive the algebraic sum f of a plurality of electrical pulses, and has for its principal object the provision of an improved system and method of operation whereby the sum of the applied pulses is indicated by the po-sition of an electron beam irrespective of the polarity of the applied pulses. v

The characteristic features of the invention are: (l) means for forming a pair of electron beams, (2) a pair of targets one of which has alternate strips of high and low secondary electron emissive material and the other of which consists of plates spaced slightly from one another, and (3) intercoupled defiectors for so controlling the movement of the two beams that one of them is moved in discretev steps across the target having alternate strips of high and low electron emissive material and in a direction dependent on the polarity of the applied pulses.

Additional objects of the invention are the provision of resistance means for intercoupling the 22 and 23 are provided for maintaining the electron guns of the devices I and II in operating condition.

Operation of device II is based on the well known principle that the net charge delivered to the target, and hence the current through the target coupling resistor, is dependent 0n the number of electrons in the beam striking the target andv on the ratio of secondary emission in the region of bombardment. If the ratio is greater than unity and there is a positive collecting iield present (in this case there is, it being provided different targets and beam deiiectors, and the provision of targets which present diiierent symmetrical patterns to the different beams.

The invention will be better understood from the following description considered in connection with the accompanying drawings and its scope is indicated by the appended claims.

Referring to the drawings:

Figure 1 is a wiring diagram of a computer system constructed in accordance with the invention, and

Figure 2 illustrates a constructional detail of Fig. 1.

The system of Fig. 1 includes a cathode ray device II) (hereinafter called the control tube) and a cathode ray device I I (hereinafter called the stepping or indicating tube).

The stepping tube I I (in which the position of the electron beam indicates the algebraic sum of the applied pulses) includes an electron gun I2 for forming a beam of electrons, a target I3 having alternate Aareas I4 and I5'(see Fig. 2) of high and low secondary electron emissive material, a pair of deectors I6 and I 1 for moving the electron beam up and down along the target I 3, and a pair of electrodes I8 and I9 for collecting the secondary electrons emitted by the areas I4 and I when they are struck by the electron beam. The low emissive areas may be of carbon and the high emissive areas may be aluminum. A source of potential is provided for maintaining the collectors I 8 and I9 at a predetermined positive potential and a power supply unit 2| and resistors lby the two collectors I8 and I9) an excess of electrons leaves the target and the net current dierence between the beam current and secondary current is supplied through the target resistor. A voltage therefore appears across this resistor making the target positive with respect to the source of target potential. If the beam strikes a region wherein the secondary emission ratio is less than unity, the net difference of current between the primary and secondary electrons supplied through the resistor is reversed and the potential of the target drops below that of the supply. If the beam is on a boundary between high -and low secondary emission, it may be divided so that the net current on the high secondary emission side is equal to the net on the low secondary emission side and no resultant current ows in the resistor so the target potential is the same as that of the supply. This variation in potential of the target potential, as hereinafter explained, is utilized to iniiuence the deiiection of the beam in device IIl.

The device I0 includes an electron gun 24 for forming a beam of electrons, a pair of electrodes 25 and 26 for deecting the beam in a horizontal direction, a pair of electrodes 21 and 28 for` deflecting the beam in a vertical direction and a target, which consists of a back plate 29 and interconnected front plates 30 and 3| which are slightly spaced from the back plate 29. It willr be noted that the back member 29 and the front members 30 and 3| are so arranged with respect to one another as to present to the control beam 40 a symmetrical pattern, this pattern being formed by the upper half of the member 29 and the member 30 and also by the member 3I and the exposed triangular area at the lower corner are also applied through resistors 35 and 36 to the vertical deiiector 21 of the device IU which is connected through a lead 31 to the target I3 of the device I I. The interconnected front plates 30 and 3| of the target of the device I9 are grounded through a resistor 38 and are connected to the deector I 6 of the device II. The back plate 29 is grounded through a resistor 39 and is connected to the deector I1 of the device.

With these connections and with no pulse applied to the terminal 32, the beams of the devices are stabilized at the points indicated by the broken lines 40 and 4I, the beam 4U being equally divided between the plates 29 and 3i and the beam 4I being equally divided between a high emissive area I4 and a low emissive area I5.

The application of a positive pulse to the terminal 32 moves the beam of the device I0 upward and to the left, the pulse being of suiilcient potential to overpower the negative potential produced by movement of the beam of the device Il onto a low emission area I of the target I3. As the beam 40 moves onto the back plate 29, the deector I1 becomes more negative and the beam 4I is deected to the next high emissive area, thereby making the potential of the target I3 more positive and facilitating the movement of the beam 40 to the front plate 39. As this plate 30 becomes more negative, the deflector IB oi' the device lII becomes more negative and the upward movement of the beam 4I is arrested.

Since the applied pulse is only great enough to start the control beam over the plate 29, the above condition (where the control beam 40 on the boundary between plates 29 and 30 and the stepping beam 4I rests on a boundary between the areas I4 and I5 with the high emissive area I4 above and the low emissive area I5 below) is stable so long as the applied pulse is near its maximum.

When the applied pulse subsides, however, the control beam 40 moves to the right and downward striking the plate 29, making the electrode I1 more negative and moving the stepping beam upward until it comes to rest at the next boundary between an area I4 and an area I5 with a low emissive area above and a high emissive area below. At the same time, the control beam 40 is moved downward across the plate 29 to its illustrated stable position on the boundary between the plates 29 and 3|, Successive positive pulses applied to the terminal 32 thus operate to stabilize the stepping beam 4| at successive boundaries which have a low emissive area above and a high emissive area below.

The eii'ect of a negative pulse applied to the terminal 32 is similar to that described above -with the exception that: (l) the control beam 40 is driven downward and to the right until it reaches the boundary in the notch in the lower right hand corner of the plate 3l, and (2) the beam 4I is stepped downwardly instead of upwardly as in the case of the positive pulse.

The invention thus affords a ready means of deriving the algebraic sum oi a number oi' applied pulses irrespective of their polarity. It is apparent that the various parts of the devices I9 and I I may be enclosed within a single envelope if desired and that the target I3 may have any desired number or arrangement of its high and low emissive areas.

We claim as our invention:

1. The combination of means for producing a ilrst electron beam, a first target including members of diierent coniiguration slightly spaced from one anoth'er, means for producing a second electron beam, a second target including alternate areas of low and high secondary electron emission, means maintained at a positive potential for collecting the electrons emitted from said areas, means for moving said ilrst beam on said iirst target in response to the application of pulses to be counted. means responsive to said movement for moving said second beam across one pair of said alternate areas for each of said pulses, and means responsive to change in the potential of the second of said targets for modifying the movement of said first beam.

2. The combination of means for producing control and counting electron beams, a ilrst target including back and front members spaced from one another and shaped to present a symmetrical pattern to said control beam, a second target having alternate areas of high and low secondary electron emission, means maintained at a positive potential for collecting secondary electrons emitted from said areas, means for moving said control beam from said front member to said back member in response to applied pulses, and means responsive to said movement for moving said counting beam across said areas.

3. The combination of means for producing control and .counting electron beams, a first target including back and front members spaced from one another and spaced to present a symmetrical pattern to said control beam, a second target having alternate areas of high and low secondary electron emission, means maintained at a positive potential for collecting secondary electrons emitted from said areas, means for moving said control beam from said front member to said back member in response to applied pulses, means responsive to said movement for moving said counting beam across said areas, and means responsive to electrons emitted from said areas for modifying the movement of said control beam so that said counting beam is moved across adjacent pairs of said areas in response to each of said pulses.

4. The combination of means for producing control and counting electron beams, a iirst target including back and front members spaced from one another and shaped to present a symmetrical pattern to said control beam, a second target having alternate areas of high and low secondary electron emission, means maintained at a positive potential for collecting secondary electrons emitted from said areas, means for moving said control beam from said front member to said back member in response to applied pulses, means responsive to said movement for moving said counting beam across said areas, and means responsive to the electrons emitted from said areas for continuing the movement of said control beam'so that said counting beam is moved across said areas in one direction in response to positive pulses and in the opposite direction in response to negativepulses.

5. The combination of mean for producing control and counting electron beams, a first target including back and front members spaced from one another and shaped to present a symmetrical pattern to said control beam, a second target having alternate areas of high and low secondary electron emission, means maintained at a positive potential for collecting secondary electrons emitted from said areas, means for moving said control beam from said front member to said back member in response to applied pulses, means responsive to said movement for 5 moving said counting beam across one of said low emission areas to an adjacent high emissive area, and means responsive to electrons emitted from said adjacent high emissive area for continuing said movement to said front member.

6. The combination of means for producing rst and second electron beams, a rst target, means for applying pulses to be counted, means for moving the rst of said beams on said rst target in response to the application of said pulses, a second target having alternate areas oi high and low secondary electron emission, and means controlled by said rst beam to move said second beam by discrete steps from one to another of said high secondary electron emission areas and in a direction dependent on the polarity of said pulses.

7. The combination of means for producing rst and second electron beams, a rst target, means including separate pairs of deectors for moving the iirst of said beams on said rst target in a direction dependent on the polarity of pulses applied to said deiectors, a second target having alternate areas of high and low secondary electron emission, and means including a, single pair of deectors connected to said irst target for moving said second beam by discrete steps from one to another of said high secondary electron emission areas in response to each of said pulses.

8. The combination of means for producing :Erst and second electron beams, a rst target, pairs of deectors for moving said rst beam on said rst target in different directions, common means for applying pulses to said pairs of deiiectors, a second target having alternate areas of high and low secondary electron emission, and means connected to said rst target for moving said second beam on said second target by discrete steps from one to another of said high secondary electron emission areas and in a direction dependent on the polarity of said pulses.

RICHARD L. SNYDER, JR. ROBERT R. GOODRICH.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,036,350 Montani Apr. 7, 1936 2,102,139 Vance Dec. 14, 1937 2,130,134 Iams Sept.13, 1938. 2,131,886 Francis Oct. 4, 1938 2,142,541 Vogel Jan. 3, 1939 2,186,388 Moritz, Jr. Jan. 9, 1940 

